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Restoring the iconic San Michele bridge for the next century


The San Michele bridge is regarded as a symbol of industrial archaeology and one of the most interesting achievements of Italian engineering in the 19th century. 

Built in 1889, the 266m (872ft) long iron bridge, which is also known as Paderno’s bridge, was constructed from 2,500 tonnes of riveted beams held together by 100,000 nails! 

In the early 90s, the bridge was deemed structurally obsolete, and inadequate to carry the amount of road and railway traffic across the Adda river about 50km (31mi) from Milan, Italy.

There were talks to restore the bridge with a budget of 42 billion Italian lire at that time but the proposal fell through. However, a new redevelopment plan was announced by the end of 2015. 

A total of 25 million euros was allocated to restore the overall structure and upgrade it to support higher-speed rail transit – by increasing the speed from 15km (9mi) per hour to 75km (47mi) per hour, and improve the safety of pedestrian crossings. 

The bridge repair was awarded to Impresa Luigi Notari, an established construction company in Milan. GMA’s PremiumBlast™ garnet was used in the abrasive blasting of the steel structure.

Before switching to GMA Garnet™, the company has tried and tested several abrasive products such as slag abrasives. 

They found GMA Garnet™ to be most suited for their requirements for delivering higher cleaning rate while reducing abrasive consumption. 

GMA Garnet™ is a natural mineral which is inert and non-toxic and therefore leaves minimal impact on the environment. 

This was perfect for the project as the bridge is located within a nature park, and the park authorities would have insisted on using environment-friendly products only. 

On 29 March 2019, the bridge opened for bicycle and pedestrian traffic and vehicles on 8 November 2019 while train runs will commence in quarter three of 2020. 

The San Michele bridge was also nominated as a transnational asset along with four other 19th-century iron arched bridges to be included in the UNESCO heritage list in 2017. 


TGERCinquini  By Riccardo Cinquini, GMA Europe